Jessop, Philip G., Richard A. Brown, Pamela Pollet, Erin McKoon, Truc Ngo, Charles A. Eckert, Charles L. Liotta. THE USE OF NEOTERIC SOLVENTS FOR HYDROGENATION AND OTHER ASYMMETRIC REACTIONS
Department of Chemistry, University of California, Davis, CA 95616-5295 (jessop@chem.ucdavis.edu)
Schools of Chemistry and Chemical Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0100
The enantioselectivity of homogeneously-catalyzed reactions is dependent on a number of parameters, including the solvent’s polarity, transport properties, and ability to dissolve gases. Attempts to find appropriate neoteric solvents for reactions will have to balance the requirements of the reaction against catalyst recoverability without sacrificing "greenness". This strategy will be described with examples from asymmetric hydrogenation and other reactions.
For example, the Ru(O2CMe)2((R)-tolBINAP)-catalysed hydrogenation of tiglic acid in ionic liquid proceeds with high enantioselectivity. Extraction with scCO2 cleanly separates product from catalyst. The catalyst/ionic liquid solution was reused repeatedly without loss of enantioselectivity or conversion.